Fig. 2, a, a metal roller revolving on bearings, which can be raised or lowered by the screw b; c another roller, revolving in a fixed bearing; this roller is set in motion by the toothed wheel d on its axis, which is driven by the wheel e, the latter receiving its motion from the prime mover. f f an endless web of felt, passing round the small rollers g gg, and between the rollers a and c; h the reel, turned by a pulley k on its axis; the latter is driven by a band passing over it, and a pulley on the axis of c.
The operation of the machine is as follows: the pulp flows from the box 3 into the box 4, thence is distributed by the leather on to the wire web; on arriving at the cylinder d the paper receives a considerable degree of pressure upon its external surface from the atmosphere, owing to the air being rarefied in the interior of the cylinder by means of an air pump attached to the pipe 4; and the paper is thus deprived of the principal part of its water. The continuous sheet of paper then passes between the rollers h and k, and thence on to the endless web of felt, when the remaining water it contains is pressed out by the rollers a and c, Fig. 2, preparatory to its being coiled upon the reel h.
Fig. 3, a section of the cylinder d. d is the exhausting cylinder, of brass, and pierced full of holes; c e end pieces bolted to d, and carrying toothed wheels upon their peripheries; f f a hollow fixed centre, upon which d revolves, and bent into the form of a crank; g a trough composed of an iron bottom with wooden sides, and having two movable end pieces h h, which are set to the width of the paper; the whole is covered with leather; this trough is supported by the standards i i i fixed into the axis f f, and is pressed by spiral springs against the cylinder d; I a pipe fitted into the bottom g, the outer end plunging in water. m a pipe pierced full of holes, and leading to the air pump.
Mr. John Dickenson, of Nash Mills, Hertfordshire, to whom also the public stand indebted for several improvements in the paper manufacture, took out a patent in 1829 for "a new improvement in the method of manufacturing paper by machinery, and also a new method of cutting paper or other materials into single sheets or pieces, by means of machinery." From a perusal of the specification, we find these to consist, first, in causing the paper to be pressed between two rollers, the upper of which is to be heated by steam in the usual way, first with one side, and afterwards with the other upwards, to give it an equal gloss on both sides; secondly, to introduce, during the manufacture, into the centre of the paper, threads, fine net, or other reticulated material; and thirdly, to cut it into a sheet of appropriate size, by a more convenient and expeditious method than those now in use. The first object he effects by carrying the paper upon felt, round a series of rollers, similar to those employed in the double machines for printing both sides of a sheet of paper at one time; the second, by placing over the pulp vessel a series of bobbins with thread, or a roller with any other material to be introduced into the paper.
These threads are guided, by a grooved roller, into the pulp close to the first or feeding roller, which takes up the pulp to form the paper, and, by the current of the pulp approaching the feeding roller, the threads are brought into contact with it. The third improvement he effects by affixing to the bottom of a tall, oscillating frame, a series of circular revolving cutters; and when this frame is made to oscillate, and the cutters to revolve, they traverse along the edge of stationary cutters, on which the paper to be cut is extended, and thus the advantages of a clipping action is obtained.
In a subsequent patent granted to the last-mentioned Mr. John Dickenson, in October 1830, for an improvement upon his previously patented machinery, his object is to make thicker paper of a better quality than could be produced by the existing mechanism. To obtain this result, he employs two cylinders for taking up the pulp from separate troughs at the same time, from each of which a web of wet paper is conveyed, by means of endless felts, to a pair of rollers, where they are united by pressure, the subsequent manufacture of the paper being completed in the usual manner. To have a clear idea of this arrangement, it is only necessary to consider, that a duplicate of the pulp cylinder of the common machines is introduced in any convenient situation, governed by the localities of the mill; and that it is actuated by the same machinery which turns the first cylinder.
In the month following the grant of the last-mentioned patent, another was obtained by Mr. John Hall, jun., of Dartford, for "a machine upon a new and improved construction for the manufacture of paper," which we find, by a perusal of the specification, to be for precisely the same object as Mr. John Dickenson's; but the process adopted by Mr. Hall is much more elegant and scientific. In order to collect to the surface of the main cylinder of the machine a quantity of pulp sufficient to make paper of any required thickness, Mr. Hall employs an hydraulic pressure, in the following manner: - the cylinder is made to turn in a vessel supplied with pulp on the one side, and clean water on the other, which rises considerably on its exterior, and through the axis, which is made hollow for the purpose, and has a bent pipe extending from it to the lowest part. The water is continually pumped from the interior of the cylinder; and thus, by the difference in the altitude of the water inside and outside, an hydraulic pressure will be obtained, variable at pleasure, and available in causing a greater or less quantity of pulp to adhere to the surface, which is covered with wire-gauze, supported by strong ribs, to admit of the passage of the water from the exterior to the interior.